Moving apparatus for a load

ABSTRACT

A moving apparatus for a load has a speed control circuit and a torque control circuit, each circuit controlling a motor for lifting the load. When operation of the speed control circuit is stopped, the torque control circuit stores the value of the torque which is equal to the weight of the load and keeps the torque from the motor at a constant value in response to the weight of the load. In this way, the load can be moved as if it were located in a gravity-free state.

United States Patent I .loraku et a1.

1451 Oct. 15, 1974 MOVING APPARATUS FOR A LOAD Inventors: Masami .loraku, Tohkai-Mura; Seizi Yomekura, Hitachi; Shigeyoshi Kawano, Hitachiohta, all of Japan Filed:

Dec. 22, 1971 Assignee: Hitachi, Ltd., Tokyo, Japan Dec. 22, 1972 Appl. No.: 317,773

Foreign Application Priority Data Japan 46-104818 References Cited 11.8. C1. 254/127, 254/173 Int. Cl. B661 3/110, B66f l/OO Field 01' Search 254/127, 4 R, 173, 124;

UNITED STATES PATENTS Wilcox 214/142 3,713,544 H1973 Wallace et a1 214/142 X FOREIGN PATENTS OR APPLICATIONS 98,274 6/1961 Netherlands 254/127 Primary Examiner-Othell M. Simpson Attorney, Agent, or Firm-Craig & Antonelli [57] ABSTRACT 17 Claims, 16 Drawing Figures PAIEMEMB 384L605 SHEET 10? 6 PAIENTEUum 1 51924 SHEEI 30? 6 PATENIEDUCI 5 15m SHEEI U 0F 6 VOLTAGE comm k CIRCUIT PATENIEBHBT 1 51874 SHEET 6 BF 6 FIG. 90

' MOVING APPARATUS FOR A LOAD BACKGROUND OF THE INVENTION This invention relates to a moving apparatus for a load and, particularly, to an apparatus for moving a load to a desired place in a certain space with a small external force.

A conventional moving apparatus lifts a load in response to an on or off operation of a switch. The lifted load cannot be moved by a man directly, since the control means of the conventional moving apparatus operates so as to add force in an opposite direction to the external force. When the designated speed is zero speed, the control means operates so as to keep the load at a constant position. If an external force tending to lift the load is applied to the load, a motor produces a force in the opposite direction in response to an out put from the control means in order to keep the load in position. If the operator wants to move the load, he must operate the switch or a speed designating circuit.

Since the load cannot be moved directly by hand, the operator cannot move the load precisely to the desired position and cannot stop it precisely at the desired level. For example, a conventional moving apparatus is used for lifting heavy parts which are used to assemble a machine. The parts must be stopped at certain positions for assembling the machine without colliding with each other. This operation is very difficult. As a result, it is desirable to move the load by hand directly as if the load were located in a gravity-free state.

SUMMARY OF THE INVENTION Object of the Invention The primary object of the invention is to provide an apparatus for moving a load precisely without much power.

The second object of the invention is to provide an apparatus for moving a load in a certain space as if a load were located in a gravity-free state.

The third object of the invention is to provide a moving apparatus having a very small frictional resistance.

Statement of the Invention If a force having a magnitude equal to the weight of a load acts on the load in an opposite direction to the weight, when a man wants to lift the load, the load can be lifted with only a small additional force. If the mechanical friction of the lifting device is also negated by another force, it is easier to move the load.

The moving apparatus of the present invention has force control means and speed control means, the force control means storing the weight of a load and maintaining the generation of a desired force which is needed to lift the load, and the speed control means maintaining the speed for moving the load at an appointed value.

When a load is in a suspended or lifted position, its

appointed speed is zero, and the load is stopped at that position. In this condition, the force control means stores the weight of the load and generates a force needed for suspending or lifting the load. If an external force having a tendency to move the load is applied to the load, the speed control means operates to generate a force which acts on the load in the opposite direction to the external force in order to stop the movement of the load in response to the value of the appointed speed.

When a man wants to move the load to a desired position by hand, the operation of the speed control means is stopped in order that the speed of the load can become independent of the appointed speed. Since the force control means stores the weight of the load, the load is lifted or suspended with a certain force. If a man applies the same force for moving the load, the load can be moved with some speed. Namely, since the force produced in response to an output from the control means is equal to the weight of the load, all of the force provided by the man is used for moving the load where it is assumed that the mechanical friction of the moving apparatus is neglected.

When the load is moving to a position with some appointed speed in response to an output from the speed control means, if the operation of the speed control means is stopped, the load maintains its movement with the appointed speed until an external force is applied to the load.

In the above explanation, the mechanical friction of the speed control means is neglected, but in practice the mechanical friction is considerable. The apparatus of the present invention has a compensating means for mechanical friction in order to move the load with a small force. Namely, the compensating means operates so as to apply to the load a force corresponding to the frictional force, but in the opposite direction.

There are two methods for solving the problem of compensating for mechanical friction. According to one method, the force control means stores the real weight value of the load and the compensating means compensates only for the mechanical friction. According to another method, the force control means stores the real weight value of the load and the mechanical friction force. The compensating means calculates the needed compensating value from the value of the real mechanical friction and the value of the stored mechanical friction force.

In the first method, since a force corresponding to the value which is produced by adding the stored value with value of frictional force exists in equilibrium with an observed weight of the load, the: memorized value is decided.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view of a mechanism in accordance with one embodiment of the invention.

FIG. 2 is a plane view of the mechanism of FIG. 1.

FIG. 3 is a schematic block diagram of a control means in accordance with an ambodiment of the invention.

FIG. 4 is a detailed circuit diagram of the force control system and the speed control system of the control means of FIG. 3. r

FIG. 5 is a schematic circuit diagram of a voltage supply circuit for the motor and the control means of FIG. 3.

FIG. 6 is a schematic circuit diagram of a relay circuit for operating the circuits of FIG. 4 and FIG. 5.

FIGS. through 7c are schematic diagrams for explaining the mechanical friction when a load is lifted up.-

FIGS. 8a through 8c are schematic diagrams for explaining the mechanical friction when a load is lowered down.

FIGS. 9a through 90 are detailed circuit diagrams of compensating circuits for mechanical friction force.

FIG. is a detailed circuit diagram of a compensating circuit for a dynamic frictional force.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 and FIG. 2, a lifting assembly includes four arms 1, 2, 3 and 4, pivotally connected at 5, 6, 7 and 8 to form a parallelogram linkage. The connection point 8 is supported movably by a first supporting pole 20. A load 10 is lifted by an end of the arm 2. The lifting assembly is balanced by applying to an end 11 of the arm 1 a force corresponding to the weight of the load 10.

The end 9 of the arm 2 can be moved in a certain space defined by points a, b, c and (1, since the ratio of the distance between the connected points 8 and 11 and the distance between the connection points 8 and 9 is always constant. a

The end 11 of arm 1 is pulled by chain 12 which is wound on a sprocket 16 fixed on a shaft of a motor 13. A guide wheel 14 fixed on the end of the arm 1 moves up or down along guides 15. A frame 17- having wheels 18 is free to move along a guide 19 which is rotatably fixed on the first supporting pole 20 and a second supporting pole 21. The first and second supporting poles 20 and 21 are supported by a base 23 through a main pole 22.

Referring to FIG. 3, when a contactor 303 is switched on, an output corresponding to a designated speed from a speed designating circuit 301 is compared with feed back information from a speed detector 311 at a summing point 302 and is applied to an operational amplifier 304. An output from the operational amplifier 304 and an output from a current detector 307 are applied to each input terminal of an operational amplifier 305. A current converter 306 controls the current supplied to a motor 316 in response to the output from the operational amplifier 305. Then, a load 310 lifted by a chain 312 is moved by a moving body 313, such as a sprocket or a pulley,'which is fixed on a shaft of the motor 316. The value of the current drawn by the motor 316 is fed back to the operational amplifier 305 through the current detector 307. The value of the speed of the motor 316 is applied to the summing point 302 through the speed detector 311.

When the output from the speed designating circuit 301 has a high value, the load 310 is lifted up. While, if the output from the speed designating circuit 301 is of small value, the load 310 goes down. When the output is represented by an intermediate value, the load is stopped. Namely, when the output from the speed designating circuit represents zero speed, the load is stopped at its position. In this case the output of the operational amplifier 304 represents zero speed. The value of current corresponding to the torque of the motor 316 needed for lifting the load 310 flows into the motor 316 and is stored in the operational amplifier 305. In order to keep the value of the motor current constant. the output of the current detector representing the motor current value is fed back to the operational amplifier. The power control means consisting of the operational amplifier 305, the current converter 306 and the current detector generates the output corresponding to the weight of the load 310. Namely, in order to control the load 310 as if it were balanced with an imaginary load 314 of equal weight to the weight of the load 310, the motor applies power to the sprocket 313 in response to the output from the power control means.

The speed control means consisting of the speed designating circuit 301, the speed detector 311, the summing point 302 and the operational amplifier 304 generates an output power of the motor representing all that is used for moving the load, upward or downward,

.if the frictional force is negligible. Since the speed of the motor is fed back as an information through the speed detector 311, the speed of the motor is kept at a designated value by the operation of the speed control means.

When the contactor 303 is switched off, the operation'of the speed control means is stopped. Then, the

motor is free to move in position. If the frictional force is negligible, all of the external force is used for moving the load.

Referring to FIGS. 4, 5 and 6, terminals 401 and 402 of the variable resistor 403 are connected to terminals 520 and 521 of a voltage control circuit 516, respectively. A. sliding contact having a terminal 408 is connected to a summing point 405 through a resistor 404. A terminal of a generator 407 having a terminal 409 is connected to the summing point 405 through a resistor 406 and a contactor B A command signal from the variable resistor 403 is compared with the instantaneous voltage from the generator 407. The result of this comparison, an output of the summing point 405 representing anerror, is applied to input terminal 410 of an operational amplifier 414. Another input terminal 411 of the amplifier 414 is grounded through a resistor 415. Terminals 416 and 417 are connected to the terminals 520 and 521 of the voltage control circuit 516. A series circuit of a resistor 412 and a capacitor 413 is connected between the terminal 410 and an output terminal 418 of the amplifier 414.

The system consisting of the variable resistor 403, the

summing point 405, the generator 407 and the amplifier 414 operates as the speed control means. The output of the speed control means is applied to an input terminal 421 of an operational amplifier 427, which has a capacitor 425 and resistor 426 for storing the power of a motor 506 needed for lifting a load. Another input terminal 422 is connected to a terminal 541 (FIG. 5) of a rectifier circuit 540 through a resistor 440 and terminal 441. An output terminal 430 is connected to bases of transistors 463 and 463A through resistors 462 and 462A, respectively. A bidirectional Zener diode 435 is connected between the terminal 430 of the operational amplifier 427 and ground.

Terminals 445 and 445A are connected to the terminal 520 of the voltage control circuit 516 and terminals 446 and 446A are connected to the terminal 521. Terminals 450 and 450A are connected to terminals 511 and 512, respectively. When the voltage of the terminals 511 and 512 is nearly equal to zero, current through a resistor 454 flows to the terminal 511 through the terminal 450, a resistor 451 and a diode 453. The charged voltage of the capacitor 452 is zero value. Since the voltage of the terminal 511 is increased, the base current of a transistor 456 through a diode 455 is increased. Then, when the voltage of the terminal 511 reaches a certain value, the transistor 456 is turned on and the base voltage of the transistor is lowered through a resistor 457. The collector current of the transistor 459 flows through a resistor 460 in response to the value of the base current of the transistor 459 flowing through a resistor 450. The collector voltage of the transistor 459 is applied to the base of a transistor 463 through a resistor 461. When the collector current of the transistor 459 has a large value, a high potential is applied to the base of the transistor 463, and then the transistor 463 is turned on.

The output of the operational amplifier 427 is also applied to the base of the transistor 463. Since the potential of the collector of the transistor 459 is increased along a certain characteristic curve, the time of the turning on operation of the transistor 463 is changed by the potential at the output terminal 430 of the operational amplifier 427. Namely, when the potential of the output terminal 430 has a negative value, the time of the turning on operation lags and the position potential advances the time of the turning on operation. The

emitter of the transistor 463 connected to the resistor 464 is connected tothe base of a transistor 468 through diodes 465 and 467. The base and collector of the transistor 460 are connected to the terminal 445 through a resistor 46b and a resistor 470, respectively. The base and collector of the transistor 469 are connected re spectively to the collector of transistor 460 and terminal 511 through a diode 472, a resistor 471, and terminal 473. The increasing potential of the terminal 511 is stored by a capacitor 475. When the transistor 469 is switched on by the turning on operation of the transistor 468, the charge on the capacitor 475 flows in a circuit consisting of the transistor 469, ground and a primary winding of the transformer 476, so as to cause a pulse voltage between terminals 477 and 478 and terminals 479 and 430 for turning on a thyristor 530, 531, 532 and 533. a

The base of a transistor 456A is connected to the terminal 521 through diodes 453A and 455A connected to a resistor 454A, a resistor 451A connected to 21 capacitor 452A and terminal 450A. A collector of the transistor 4556A is connected to the terminal 445A through resistors 457A and 450A connected to the base of a transistor 459A. The collector of the transis tor 459A is connected to the base of a transistor 463A and a negative voltage supply 521 at terminal 446A through a resistor 46IA and a resistor 460A, respectively. The base of the transistor 463A is connected to the collector of the transistor 459A and the output terminal 430 of the operational amplifier 427. The emitter of the transistor 463A is connected to the base of a transistor 468A through diodes 465A and 467A connected to a resistor 466A and to the terminal 446A. The collector of the transistor 468A is connected to the base of a transistor 469A and the terminal 445A through a resistor 470A. The collector of the transistor 469A is connected to the terminal 512 through a resistor 471A, diode 472A and terminal 473A and to a primary winding of a transformer 476A through a capacitor 475A. Terminals 477A, 478A, 479A, 480A are connected to the gates of the thyristors 532 and 531.

Terminals 501 and 502 are connected to an external voltage supply, and alternating voltage is applied to a transformer 510, a second winding of which having two terminals 5 ll and 512 is connected to the voltage control circuit having terminals 520 and 521 through a rectifier circuit 515. A motor 506 is connected to the terminals 501 and 502 through the thyristors for controlling motor current, a current transformer 504 and a contact A A field winding 505 of the motor is connected to the terminals 501 and 502 through a rectifier circuit 503. The relay circuit of FIG. 6 is connected between the terminals 520 and 521.

When a switch S. is switched on, since relays A B are energized, the contact A, is turned on and the contacts 8, and B are turned on. The output from the variable resistor 403 representing a designating speed is applied to the operational amplifier 414 and applied to the force control circuit. The output of the operational amplifier 427 controls the times of pulse generation from the secondary winding by controlling the switching time of the transistors 463 and 463A for controlling current drawn into the motor 506. The changing value of the motor current is fed back to the operational amplifier 427 through the current transformer. When a load is lifted to a desired position by the motor 506, the motor is stopped by returning the slidable terminal of the variable resistor 403 to zero speed level in order to stop the load at the lifted. position.

When switches S and 8;, are actuated, a timer relay is energized. Then, after a certain time, a contact TM is turned on. Since relay C is energized, a contact C is turned on and a contact C is turned off. Since the relay B is opened, the contacts Bi, and B are disconnected. Since the output from the summing point 405 is stopped, in response to the charge level of the capacitor 425 of the operational amplifier 427, the output of the force control means is regulated. Then, the motor 506 generates a force which is equal to weight of the load. Since the operation of the speed control means is stopped by opening the contacts B and B the load is independent .of its speed and position.

Referring to FIG. 7(a), when a load 10 is to be lifted up, a sprocket l3 fixed on a motor 16 winds chain 12 which lifts the load through a movable sprocket 24. If a frictional factor is ,u, a frictional force ,uW is produced in direction of the arrow in FIG. 7(a). Therefore, as the motor 16 generates a torque: W [.LW, the operational amplifier stores a weight value of the load 10 as a weight W ,uW.

Referring to FIG. 7(b), when the operation of the speed control means is stopped, if the load 10 is moved by hand in a down direction, power 212W is needed for moving the load, since the additional friction force of the stored friction .LW and the actual friction uW is generated in the arrow direction. While, if the load 10 is moved in an upward direction, since the stored value of friction ,uW and the actual friction uW act in opposite directions, all of the force applied by hand is used for moving the load 10 as shown in FIG. 7(b). But in practice a small amount of force is used to overcome friction, because real frictional force has hysteresis characteristics.

Referring to FIGS. 8(a), 8(b) and 8(0), when the sprocket l3 fixed on the motor ll6 moves the load 10 by way of the chain 12 and the movable sprocket 13 in down direction in response to the output from the speed control means, the output from the motor 16 has a value of W uW, since the frictional force aw is generated in an arrow direction. When the operation of the speed control means is stopped and the load is moved in the down direction, the value of force ZuW is needed for overcoming the additional force of stored frictional force uW and actual frictional force uW, as shown in FIG. 8(b). While, if a load is lifted by hand, as shown in FIG. 8(c), since the actual friction force MW is directed in the opposite direction with respect to the memorized frictional force W all of the force applied by hand is used for moving the load. But in actual practice, since the frictional force has hysteresis characteristics, a small force is needed for overcoming friction.

In the above explanation, the changing value of the frictional factor in response to the moving speed is neglected. When a man moves the load, at the beginning thd frictional factor has a large value and in a moving stage the frictional factor is reduced to a small value. Therefore, in more ideal apparatus, at the beginning of an operation, the value provided by a compensating means becomes large, and in the moving stage, the operation is decreased.

Referring to FIG. 9(a), an operational amplifier 903 for compensating for the frictional force is connected to resistors 902, 904, 905, 906 and terminals 901, 915 and 916, the terminal 901 being connected to the terminal 418 of FIG. 4. A switching circuit has resistors 907, 908, 909 and 910, contacts GS, GR, D,, D F and F and terminals 111 and 112, the terminal 111 being connected to the terminal 422 of FIG. 4 and the terminal 112 being connected to the terminal 421 of FIG. 4. When the load is moved in the up direction in response to the speed designating circuit, the contact GR is turned on, while in the down operation the contact GS is turned on. When the speed control circuit is operated, and the contacts D,, D F,, F are opened, the output of the operational amplifier 923 is disconnected. When the operation of the speed control means is stopped and a man moves the load, the contacts 1),, D or F,, F are connected. When a man moves the load in the down direction, the contacts D, and D are closed. If the load was stopped after initiating the up operation in response to the speed control means, since the contact GR is closed the output of the amplifier 903 is connected to the terminal 422 through the resistor 906, the contact GR, the resistor 908, the contact D and the terminals 111. Resistors 907, 908, 909, 910 are variable resistors for adjusting the operation of the compensating means.

The contacts GR and GS are operated by the circuit of'FIG. 9(b). An operational amplifier 925 has resistors 921, 928, 930 and 924, diodes 922 and 923, a capacitor 929, terminals 920, 926 and 927 and contact C The relay circuit of FIG. 9(b) has two relays D and F resistors 936, 939, 940 and 938, diodes 935, 937, 947 and 948, capacitors 941 and 942 and terminals 950 and 951. When the contact C is switched on by the relay C of FIG. 6, the output of the generator 407 of FIG. 4 is applied to the input of the operational amplifier 925 through the terminals 410 and 920, contact C and resistor 921. When a man moves the load in the down direction, since the output of the generator 407 has a negative value, the output of the operational amplifier 925 is of positive value, which is transmitted to the transistor 943 through the diode 935. Then, the contacts D, and D are closed by energizing the transistors 943 and 946.

Referring to FIG. 9(c), an operational amplifier 925C has resistors 921C, 924C, 928C and 930C, diodes 922C and 923C, a capacitor 929C, terminals 920C, 926C, and 927C and contact B A relay circuit has one relay having two coils GR and GS, resistors 936C, 939C, 940C and 938C, diodes 935C and 937C and two diodes connected to the relay coils, capacitors 941C and 942C, transistors 943C, 944C, 945C, 946C, and terminals 950C, 951C. With the contact B closed by the relay B of FIG. 6, the output of the speed designating signal is transmitted to the input terminals of the operational amplifier 925C through the terminals 408 and 920C, contact B and the resistor 921C. When the output of the speed control means has a negative value for moving the load in the up direction, since the output of the operational amplifier 925C has a positive value, the coil GR connected to the terminal 520 of FIG. 5 is energized by turning on the transistors 943 and 946. The relay of FIG. 9(0) is a relay having the following characteristics. When the coil GS connected to the. terminal 521 is energized, the contact GS is turned on until the coil GR is energized even if the contact is opened.

FIG. 10 is a circuit for compensating for the dynamic friction having one operational amplifier 1010, resistors 1002, 1015, 1016, 1012, 1020, 1026, 1027, 1040, 1050, 1056 and 1057, two transistors 1025 and 1055, two diodes 1021 and 1051, five terminals 1001, 1013, 1014, 1030 and 1060, and a contact C The terminal 1001 is connected to the terminal 410 of the generator 407 and terminals 1030 and 1060 are connected to the terminals 421 and 422, respectively. When the output of the generator 407 has a positive value, the transistor 1025 is conductive, since the operational amplifier 1010 generates a negative voltage. The collector current of the transistor 1025 is controlled by the value of the input voltage from the terminal 410. Then, when the output of the generator 407 has a large positive value, the voltage of the input terminal 421 is decreased. While, when the output of the generator 407 has a negative value, the transistor 1055 is conductive for increasing the voltage of the terminal 422. Then, when the load is moved with high speed, the dynamic friction compensating means generates an output tending to decrease the speed of the load.

What we claim is:

1. A moving apparatus for moving a load comprising lifting means including a motor for lifting a load,

speed control means for controlling the moving speed of the load,

force control means for controlling the force applied from said motor to said lifting means to correspond to the weight of-the load, and

first means for selectively stopping the operation of said speed control means.

2. A moving apparatus for moving a load according to claim 1, wherein the force control means includes memory means for storing a signal value equal to the force needed for lifting the load.

3. A moving apparatus for moving a load according to claim 2, wherein said speed control means includes speed detecting means for detecting the speed of the motor, said force control means including force detecting means for detecting the force produced by said mo- 10!.

4. A moving apparatus for moving a load according to claim 3, wherein said speed detecting means is a generator.

5. A moving apparatus for moving a load according to claim 3, wherein said speed control means includes speed designating means for providing a signal designating the speed of movement for said load.

6. A moving apparatus for moving a load according to claim 3, further including means for compensating for the mechanical friction of said lifting means.

7. A moving apparatus for moving a load according to claim 6, wherein said compensating means includes second means for detecting the moving direction of the load to determine the acting direction of the mechanical friction of said lifting means and third means for detecting the moving direction of the load before said first means is operated.

8. A moving apparatus for moving a load according to claim 7, wherein said compensating means includes transistor switching circuit means for switching the output of the compensating means in response to the outputs of said second and third means.

9. A moving apparatus for moving a load according to claim further including dynamic friction compensating means for generating a force tending to decrease the moving speed of the load when said first means is operated.

M). A moving apparatus for moving a load comprismg:

lifting means for lifting a load;

motor means connected to said lifting means for providing a force thereto for lifting the load;

speed detecting means for detecting the rotating speed of the motor; speed designating means for providing a signal designating a desired rotating speed for the motor;

comparing means for comparing the output of the speed detecting means with the signal from the speed designating means;

current supply means for supplying a current to said motor;

current detecting means for detecting current applied to the motor by said current supply means;

a current control means for controlling said current supply means to regulate the current applied to the motor in response to the outputs of said current detectin g means and said comparing means; said speed designating means, said speed detecting means, and said comparing means comprising a speed control means for controlling the rotating speed of the motor in accordance with the signal generated by the speed designating means; and

first means for selectively stopping the operation of said speed control means.

ll. A moving apparatus for moving a load according to claim it), wherein said comparing means comprises a summing point and a first operational amplifier, said signals from said speed designating means and said 10 speed detecting means being applied to respective inputs of said summing point.

12. A moving apparatus for moving a load according to claim 11, wherein said first means includes cutoff means for electrically opening the electrical connection between said speed detecting means and said first operational amplifier, the operation of said speed control means being stopped by the operation of said cutoff means.

13. A moving apparatus for moving a load according to claim 12, wherein said first means further includes timer means operated in response to the operation of said cutoff means for stopping the operation of said cutoff means after a certain period.

M. A moving apparatus for moving a load according to claim 12, wherein said current control means comprises a second operational amplifier for providing a signal representing a current value to be applied to said motor, and a current converter for regulating the current applied to said motor in response to the signal from said second operational amplifier.

15. A moving apparatus for moving a load according to claim M, wherein said current control means further includes limiting means between said second operational amplifier and said current converter, said limiting means preventing an analog value of the output of said second operational amplifier from exceeding a certain range.

16. A moving apparatus for moving a load according to claim M, wherein said second operational amplifier has at least two input terminals, one terminal being connected to the output of said first input terminal and another being connected to said current detecting means, and a first capacitor provided between the one input terminal and the output terminal of said second operational amplifier.

17. A moving apparatus for moving a load according to claim l6, wherein said lifting means includes four arms, one end of said first arm being adapted to receive a load to be hoisted, one end of said second arm being connected to another end of said first arm, another end of said second arm being mechanically connected to said motor and being moved by the motor force in the vertical direction, one end of said third arm being connected to a point between the one and other ends of said first arm and the other end of said third arm being connected to a base, one end of said fourth means being connected to a point between the one and other ends of said second arm, the other end of said fourth arm being connected to the base, said first and fourth arms being always arranged in parallel, said second and third arms being always arranged in parallel, and said motor being supported on said base for movement in the horizontal direction. 

1. A moving apparatus for moving a load comprising lifting means including a motor for lifting a load, speed control means for controlling the moving speed of the load, force control means for controlling the force applied from said motor to said lifting means to correspond to the weight of the load, and first means for selectively stopping the operation of said speed control means.
 2. A moving apparatus for moving a load according to claim 1, wherein the force control means includes memory means for storing a signal value equal to the force needEd for lifting the load.
 3. A moving apparatus for moving a load according to claim 2, wherein said speed control means includes speed detecting means for detecting the speed of the motor, said force control means including force detecting means for detecting the force produced by said motor.
 4. A moving apparatus for moving a load according to claim 3, wherein said speed detecting means is a generator.
 5. A moving apparatus for moving a load according to claim 3, wherein said speed control means includes speed designating means for providing a signal designating the speed of movement for said load.
 6. A moving apparatus for moving a load according to claim 3, further including means for compensating for the mechanical friction of said lifting means.
 7. A moving apparatus for moving a load according to claim 6, wherein said compensating means includes second means for detecting the moving direction of the load to determine the acting direction of the mechanical friction of said lifting means and third means for detecting the moving direction of the load before said first means is operated.
 8. A moving apparatus for moving a load according to claim 7, wherein said compensating means includes transistor switching circuit means for switching the output of the compensating means in response to the outputs of said second and third means.
 9. A moving apparatus for moving a load according to claim 8, further including dynamic friction compensating means for generating a force tending to decrease the moving speed of the load when said first means is operated.
 10. A moving apparatus for moving a load comprising: lifting means for lifting a load; motor means connected to said lifting means for providing a force thereto for lifting the load; speed detecting means for detecting the rotating speed of the motor; speed designating means for providing a signal designating a desired rotating speed for the motor; comparing means for comparing the output of the speed detecting means with the signal from the speed designating means; current supply means for supplying a current to said motor; current detecting means for detecting current applied to the motor by said current supply means; a current control means for controlling said current supply means to regulate the current applied to the motor in response to the outputs of said current detecting means and said comparing means; said speed designating means, said speed detecting means, and said comparing means comprising a speed control means for controlling the rotating speed of the motor in accordance with the signal generated by the speed designating means; and first means for selectively stopping the operation of said speed control means.
 11. A moving apparatus for moving a load according to claim 10, wherein said comparing means comprises a summing point and a first operational amplifier, said signals from said speed designating means and said speed detecting means being applied to respective inputs of said summing point.
 12. A moving apparatus for moving a load according to claim 11, wherein said first means includes cutoff means for electrically opening the electrical connection between said speed detecting means and said first operational amplifier, the operation of said speed control means being stopped by the operation of said cutoff means.
 13. A moving apparatus for moving a load according to claim 12, wherein said first means further includes timer means operated in response to the operation of said cutoff means for stopping the operation of said cutoff means after a certain period.
 14. A moving apparatus for moving a load according to claim 12, wherein said current control means comprises a second operational amplifier for providing a signal representing a current value to be applied to said motor, and a current converter for regulating the current applied to said motor in response to the signal from said second operational amplifier.
 15. A movIng apparatus for moving a load according to claim 14, wherein said current control means further includes limiting means between said second operational amplifier and said current converter, said limiting means preventing an analog value of the output of said second operational amplifier from exceeding a certain range.
 16. A moving apparatus for moving a load according to claim 14, wherein said second operational amplifier has at least two input terminals, one terminal being connected to the output of said first input terminal and another being connected to said current detecting means, and a first capacitor provided between the one input terminal and the output terminal of said second operational amplifier.
 17. A moving apparatus for moving a load according to claim 16, wherein said lifting means includes four arms, one end of said first arm being adapted to receive a load to be hoisted, one end of said second arm being connected to another end of said first arm, another end of said second arm being mechanically connected to said motor and being moved by the motor force in the vertical direction, one end of said third arm being connected to a point between the one and other ends of said first arm and the other end of said third arm being connected to a base, one end of said fourth means being connected to a point between the one and other ends of said second arm, the other end of said fourth arm being connected to the base, said first and fourth arms being always arranged in parallel, said second and third arms being always arranged in parallel, and said motor being supported on said base for movement in the horizontal direction. 